JPH10109157A - Plugging structure into nozzle hole for adjusting flow rate and method for opening nozzle hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the excess sintering of plugging material and the penetrated solidification of molten steel into the plugging material and to eliminate the clogging of a nozzle by inserting a sheet-like refractory or a sheet-like refractory containing carbon between the plugging materials. SOLUTION: In a ladle cleaning a nozzle hole 1 after completing casting, a conical shaped steel-made cup 12 opening the lower part is inserted into the nozzle hole 1 from a plate hole at the back surface of the ladle just after cleaning. Thereafter, at the time of plugging the plugging material 6 to near the upper part of the upper nozzle 2 after returning back the ladle to the vertical state, the thermoplastic sheet-like refractory 8 containing the carbon is laid at the upper part and the plugging material 6a is further laid thereon to insert the sheet-like refractory 8. In this condition, e.g. after preheating for about 30min, the molten steel of 240t from a converter is received, and after receiving the molten steel, an RH treatment is executed at two times, and after passing through about 120min since receiving the molten steel, gaseous argon is blown from the plate hole at 9kg/cm<2> pressure and 500Nl/min flow rate for about 3min and the nozzle is opened to start casting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate adjusting nozzle for a molten metal container, in which a filler is filled in the nozzle hole to prevent the nozzle hole from being clogged when molten steel flows out. This is the hole opening method.

[0002]

2. Description of the Related Art For example, a ladle for molten steel is provided with a sliding nozzle device having a sliding plate in which a nozzle hole is formed, and the sliding plate is slid to adjust the flow rate when the molten steel flows out.

FIG. 4 is a view showing a conventional filling structure in which a filler is filled in a nozzle hole. The sliding nozzle device is composed of an upper nozzle 2 having a nozzle hole 1, a fixed plate 3, a sliding plate 4, and a lower nozzle 5. By sliding the sliding plate 4, the areas of the openings of the fixed plate 3 and the sliding plate 4 are adjusted to control the flow rate. In order to prevent molten steel from solidifying and clogging in the nozzle hole 1 during the period from the receiving of steel to the start of outflow, a filler 6 made of refractory powder is added to the nozzle hole 1 before receiving the steel. Is filled.

The filler 6 is generally made of refractory powder such as silica sand or mullite. The refractory powder in the upper layer of the filler is formed by the residual heat of a ladle or preheating up to steel receiving. The sintered layer 7 is formed before the steel is received. This sintered layer 7 prevents the refractory powder from separating and floating due to the inflow of molten steel at the time of receiving steel, and prevents the molten steel from penetrating into the filler and solidifying.
Moreover, when the sliding rate 3 is slid, the nozzle is broken by the weight of the molten steel and the nozzle hole 1 can be opened. However, when the formation of the sintered layer 7 is insufficient, the filler 6 separates and floats at the time of receiving steel, and the molten steel penetrates into the filler 6 and solidifies, so that the nozzle hole 1 is not opened. On the other hand, if the sintered layer 7 is too thick, there is a problem that even if the nozzle hole 1 is opened, the sintered layer 7 is not broken and opened due to the weight of the molten steel.

Generally, when a filler is clogged in the nozzle hole, an iron pipe is inserted into the nozzle hole and oxygen gas is blown to blow off the filler, or to melt a solidified molten steel or sintered layer. Or forcibly opening the hole. However, in this case, since a person inserts an iron pipe into the lower nozzle hole below the ladle, there is a problem that a splash may occur at the time of work or a person may be hit, which is a very dangerous work. . Further, when oxygen is blown, the inside of the nozzle hole is melted and damaged by oxygen and molten iron oxide, so that the life of the refractory is shortened. In addition, there are cases where holes are not opened even during this oxygen blowing operation.At this time, the molten steel may be transferred to another ladle or returned to the converter or electric furnace, causing a problem that the process may be significantly disrupted. Occurs.

In Japanese Patent Publication No. 57-33091, one or more refractory fine powders such as silica sand, rock, alumina, magnesia, carbon and the like are added to the surface of the filler in the nozzle hole. It describes that a sludge to which a refractory binder solution or an inorganic binder powder is added is injected and thermally cured. By this method, the molten metal is prevented from penetrating and solidifying into the filler in the nozzle hole, and sintering of the filler is prevented. And, as the inorganic binder, sodium silicate, sodium hexametaphosphate or alumina sol is used.

[0007]

However, in the method described in the above-mentioned publication, since the refractory is put into the filler surface in a state of being slushed, the sludge actually penetrates considerably into the filler. Since the inorganic binder sinters up to the filler and forms a strong sintered layer, there is a problem that the nozzle hole cannot be opened. further,
Since the thickness of the coating layer cannot be controlled due to charging with a fluid in a muddy state, there is a problem that the coating layer lacks stability and the porosity is not stable.

The present invention prevents the floating of the filler at the time of receiving steel, prevents molten steel from penetrating into the filler filled in the nozzle hole, or prevents the sintered layer of the filler from becoming too thick, and the nozzle hole is closed. In this case, it is an object of the present invention to provide a filling structure of a flow rate adjusting nozzle hole capable of forcibly removing a filler and a method of opening the same.

[0009]

SUMMARY OF THE INVENTION The present invention is to prevent the sintered layer of the filler filled in the nozzle hole from becoming too thick and to prevent the molten steel from penetrating and solidifying into the filler.
The filler filled in the nozzle hole is covered with a sheet-like refractory, and when the nozzle hole is closed, the filler is forcibly removed by discharging gas and blowing off the filler. It is characterized in that a hole is formed.

As the sheet-like refractory, a material which is softened and deformed by heating or a material containing carbon can be used.

Further, a filling structure in which a filler is further covered on the sheet-like refractory may be adopted. Further, a cup may be arranged at a lower portion in the nozzle hole.

[0012] A filling structure in which a weir is provided around the nozzle opening at the furnace bottom of the molten metal container may be employed.

The filler closing the nozzle hole discharges gas from the sliding plate before the molten steel flows out, blows off the gas, and opens the hole.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The refractory sheet is made of a material which has a relatively dense structure and which does not easily react with a filler, and a packing material which is generally used for a joining surface of a casting nozzle is used. For example, a packing material obtained by kneading and molding a mixture of a refractory powder and a fiber with addition of a low melting point metal and a binder and interposing between deformable casting refractories (Japanese Patent Publication No. No. 15592), a refractory material, a hydroxide and / or a carbonate, and a binder, and are formed at a joint between the nozzle refractory and the tuyere refractory. A joint molding having plasticity (see Japanese Patent Application Laid-Open No. 6-142859), or 100 parts by weight of a refractory powder or a refractory fiber material is used as a main raw material, and heat-expandable microbeads are used in an amount of 0.2 to 10 parts.
20 parts by weight, and 3-50 parts by weight of a resin component of a vinyl acetate emulsion and / or rubber latex as a binder.
18073). These are phenolic resin, silicone resin, furan resin, refractory powder,
It is manufactured by adding an organic binder such as epoxy resin, tar, pitch, vinyl acetate resin emulsion, rubber latex, polyethylene, and polystyrene, kneading, and rolling to a constant thickness to form a sheet. This refractory sheet is classified into a soft type and a hard type at room temperature, but is characterized by being softened and deformed by heating.

In order to soften and deform by heating, it is common to use a resin that softens and deforms by heating, such as tar or pitch, or a glass to which low melting point glass such as frit or low melting point metal powder is added. The sheet-like refractory once softens and deforms at a temperature of about 100 to 800 ° C., but hardens thereafter. In other words, after the refractory sheet is placed on the filler in the nozzle hole, it quickly softens and deforms due to the preheating in the ladle and the subsequent preheating to steel receiving, covering the filler surface and hardening after the deformation. To protect the filler. The fiber is not always necessary for the sheet-like refractory of the present invention, and can be used when it is desired to reinforce the strength or improve the shape retention, for example, due to the thickness, area, or setting method of the sheet-like refractory. . Further, in order to enhance the handleability, a material whose surface is covered with a flammable sheet or plate of paper or a polymer resin can be used.

Since the sheet-like refractory softens and deforms by heating, the sheet-like refractory softens and deforms by heating even if it is placed between the fillers, so that the surface of the filler is uniformly covered with a constant thickness. Can be. Since the surface of the filler can be uniformly covered in this way, the sintering of the filler due to a rise in temperature is suppressed, the penetration of molten steel into the filler is prevented, and the separation and floating of the filler when receiving steel is prevented. can do. In order to soften and deform by heating, a thermoplastic resin, a low melting point glass or a low melting point metal is used as described in the above-mentioned known document.

Further, the sheet-like refractory desirably contains carbon. The above-mentioned organic binder carbonizes when the temperature rises, and thus has an effect of inhibiting sintering with the surrounding filler that comes into contact with the sheet-like refractory. When an organic binder is not used, one or more of carbon black, flaky graphite, soil graphite and electrode scrap may be added.

On the other hand, the filler may be a commonly used filler and is not particularly limited. For example, one or more of refractory powders such as silica sand, mullite, alumina, magnesia, zirconia, and zircon can be used. Further, these refractory powders may be coated in advance with carbon, an inorganic binder, an organic binder, ultra-fine refractory powder, or the like.

The thickness of the sheet-like refractory is determined by the capacity of the ladle, the type of steel, the refining conditions and the like, but is in the range of about 1 to 30 mm.

However, when the nozzle hole is closed due to the progress of sintering of the filler due to the operating conditions of the ladle, gas is blown from the lower plate to blow off the filler and open the hole. . At this time, since the refractory sheet has a dense structure, the upper sintered layer can be broken by receiving gas pressure in this portion. If there is no sheet-like refractory, the gas leaks to the surface, so that the internal pressure does not rise sufficiently and the sintered layer cannot be destroyed.

Further, in order to blow off the sintered layer more reliably, a cup having a lower opening is arranged at a lower portion of the nozzle hole, and a high-pressure gas is blown out from a gas blowing portion of the plate when the cup is opened. Pressing the refractory container upwards with pressure will completely destroy the sintered layer. For this reason, the shape of the heat-resistant container is preferably a conical shape with an opening in the lower part, but may be a pyramid, a hemisphere, or a dome.

The material of the gas blowing portion is required to have heat resistance. However, since the temperature at the lower portion of the nozzle hole does not become so high, at least 500 ° C. or more is sufficient as the heat resistance. For example, it may be a metal such as steel, stainless steel, aluminum, and tinplate, or a refractory mainly containing one or more of alumina, silica, zirconia, and magnesia.

Further, in order to prevent the impact of molten steel flowing into the nozzle hole at the time of receiving the steel, a weir is provided around the nozzle hole at the furnace bottom of the molten metal container. The weirs can be provided circumferentially, but if they are provided completely circumferentially, the molten steel is not completely discharged, so they can be provided alternately or partially. The height of the weir is determined according to the size of the ladle and the steel receiving method, but it is approximately 20 to 20.
The range is 0 mm. There is no particular limitation on the material of the weir, and any refractory or the like usually used for ladles and tundishes can be used.

The gas injection structure of the sliding plate may be a structure generally used for a ladle, a tundish plate, or the like. For example, a porous brick may be buried or penetrated in the sliding surface of the sliding plate. A hole may be provided.

As the gas to be used, argon or nitrogen is preferable because of little damage to the refractory, but oxygen or air can also be used according to the processing conditions and the like. Further, the gas supply source can be used by connecting it to the factory piping, but it is also possible to hold a gas tank in a ladle.

[0026]

EXAMPLES The sheet refractories used in Examples 1 to 3 were:
A mixture having the compounding ratio shown in Table 1 was kneaded, formed into a sheet having a thickness of 5 mm, cut into a predetermined size after forming, and used.

[0027]

[Table 1] Embodiment 1 FIG. 1 is a view showing one embodiment of a filling structure according to the present invention.
The filling material 6 was filled up to the upper part of the upper nozzle 2, and the sheet-like refractory 8 was placed thereon. The sheet-like refractory 8 was set from above the pot by a handling device.

After preheating for about 30 minutes in this state, 240 tons of molten steel is received from the converter, RH treatment is performed after receiving the steel, and the slide plate 4 is slid about 60 minutes after the steel reception to slide the nozzle hole 1. Was opened to start casting, but the molten steel could flow out without closing the nozzle hole 1. 30 tests were performed with the same ladle, but the nozzle hole 1 could be used without blocking.

Embodiment 2 FIG. 2 is a view showing another embodiment of the filling structure of the present invention. In a ladle in which the nozzle hole 1 is cleaned after the casting is completed, the filler 6 is supplied to the nozzle hole 1 at the upper part of the upper nozzle 2. The mixture was filled to the vicinity, and a thermoplastic sheet-like refractory 8 containing carbon was set thereon from above the pot by a handling device. On top of this, a filler material 6 a was further placed, and a sheet-like refractory 8 was sandwiched between the filler material 6 and the filler material 6.

The refractory sheet 8 is preheated in this state for about 30 minutes, then receives 240 tons of molten steel from the converter, is subjected to RH treatment after receiving the steel, and is subjected to RH treatment 60 minutes after receiving the steel. , The casting was started with the nozzle hole 1 opened, but the molten steel could flow out without closing the nozzle hole 1. The same ladle was tested 30 times,
The nozzle hole 1 could be used without being closed.

Embodiment 3 FIG. 3 is a view showing still another embodiment of the filling structure of the present invention.

As the sliding plate 4, a sliding plate 4 provided with a gas blowing section 9 having 50 through-holes having a thickness of 0.3 mm and a width of 20 mm in the same area as the nozzle hole 1 was used. Further, a weir 11 was provided on the nozzle brick 10 with a length of 3/4 circumference centering on the hot water contact direction.

In the ladle in which the nozzle hole 1 was cleaned after the casting was completed, a conical steel cup 12 having a downward opening from the plate hole on the back of the pan to the nozzle hole 1 was inserted immediately after cleaning. Thereafter, the ladle is returned to the vertical position, and when the filler 6 has been filled up to near the upper portion of the upper nozzle 2, a thermoplastic sheet-like refractory 8 containing carbon is placed thereon, and the filler 6a is further placed thereon. The sheet-like refractory 8 was sandwiched. The sheet-like refractory 8 was set from above the pot by a handling device. After preheating for about 30 minutes in this state, 24 hours
0 t of molten steel was received, and RH treatment was performed twice after receiving the steel. About 120 minutes after receiving the steel, argon gas was supplied from the plate at a pressure of 9 mm.
Casting was started at a flow rate of 500 Nl / min for 3 minutes at a flow rate of kg / cm ² to start casting, but the molten steel could flow out without clogging. In the case where the time from receiving steel to the start of casting was as long as 120 minutes on average, 30 tests were carried out, but it could be used without any problem.

[0034]

【The invention's effect】

(1) In the nozzle hole for flow rate adjustment of the molten metal container,
By sandwiching a sheet-like refractory or a sheet-like refractory containing carbon between fillers, oversintering of the fillers and penetration and solidification of molten steel into the fillers could be prevented. lost.

(2) In the nozzle hole for adjusting the flow rate of the molten metal container, the nozzle hole is filled with a filler, and a cup having a lower opening is arranged in the lower part of the nozzle hole. A sheet-like refractory is placed on top of the sheet-like refractory, and a filler is further placed on the sheet-like refractory. After the steel is received, a gas is discharged from the sliding plate before the molten steel flows out, and the filler is blown off. Even when the time from steel to the start of casting was long, it was possible to prevent the occurrence of nozzle blockage.

(3) Since the occurrence of nozzle blockage was prevented, dangerous oxygen blowing operation was eliminated, and the working environment was improved.

(4) The return of the molten steel to the converter or the electric furnace due to the blockage trouble was eliminated, and the production process was not disturbed.

(5) When carbon is contained in the refractory sheet, the thickness of the sintered layer can be controlled without sintering with the filler.

(6) By providing a weir around the nozzle opening at the bottom of the furnace of the molten metal container, separation and floating of the filler due to the flow of molten steel at the time of receiving steel could be prevented.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a filling structure of the present invention.

FIG. 2 is a view showing another embodiment of the filling structure of the present invention.

FIG. 3 is a view showing still another embodiment of the filling structure of the present invention.

FIG. 4 is a view showing an embodiment of a conventional filling structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle hole 2 Upper nozzle 3 Fixed plate 4 Sliding plate 5 Lower nozzle 6, 6a Filler 7 Sintered layer 8 Sheet-like refractory 9 Gas blowing part 10 Nozzle brick 11 Weir 12 cup

Claims (7)

[Claims] 1. A filling structure for a flow rate adjusting nozzle hole, wherein a filling layer formed by filling a filler into a flow rate adjusting nozzle hole of a molten metal container is covered with a sheet-like refractory. 2. The filling structure for a flow rate adjusting nozzle hole according to claim 1, wherein the sheet-like refractory is made of a material which is softened and deformed by heating. 3. The structure for filling a flow rate adjusting nozzle hole according to claim 1, wherein the sheet-like refractory contains carbon. 4. The filling structure for a flow rate adjusting nozzle hole according to claim 1, wherein a filler is further covered on the sheet-like refractory. 5. The filling structure for a flow rate adjusting nozzle hole according to claim 1, wherein a cup is arranged at a lower portion in the flow rate adjusting nozzle hole. 6. A weir is provided around a nozzle opening in a furnace bottom of a molten metal container.
Or the filling structure of the nozzle hole for flow rate adjustment of 5. 7. The gas filling method according to claim 1, wherein the filler filled in the nozzle hole is supplied with gas from the sliding plate before flowing out of the molten steel. A method for opening a flow rate adjusting nozzle hole, characterized by discharging and blowing off.